Star wheel



Oct. 26, 1943. H. A. DE vRY ETAL 2,332,509

STAR WHEEL i Filed June 1 0, 1940 2 Sheets-Sheet ll 4f @Mgg CCL 26,1943. H A, DE VRY ETAL 2,332,509

STAR WHEEL Filed June 1o, 1940 `2 sheets-sheet 2 lf OO Patented Oct. 26,1943 Herman A. de vry and ott RLNemetnohiea'ge, f Ill., assignors to DeVryorporation, y( Jhicago, 4,

Ill., a corporation of Illinoisvl Lmmncation June 1o, 1940,*seria1 up.339,770 sclaims. (c1. 'MerrittIIJ The present invention-relates tosta-rwheels as used for the step-by-step feeding action ofbands or the like,and particularly l'm strips in cinematf ographic apparatus.

One object of the invention is to provide a star wheel in which theharmful results of wear between the Vpins or teeth of the wheel and thegroove or cam of the driving wheel have -been eliminated. 1

Another object istev provide astar wheel having-pins or teeth andadriving wheel `having a groove designed so that adjustment of one Wheelwith relation to the other jwill seri/fek to take up the wear due tooperation.Y

A further object'oi the invention isv to provide an improved form oftooth or pin for a star wheel adapted to resist wear more eiectivelythan those now in use. The invention also embraces means and av methodfor producing star wheels with teeth of this improved form withaccuracy, speed and economy.

Further objects and advantagesof the invention will appear to" thoseskilled in the art yfrom the following specification and theaccompanyingdrawings, representingg'by way of example,y three embodiments thereof. yIn the drawings: j vFigure 1 is a side elevation showing a multiplepinstar wheel cooperating*withaone-groove cam, the view being taken partlyinl section.I r

Figure 2 is a top Vplan view of the star and cam shown in Figure l,butwith a portionIv ofthe cam wheel broken away, and withfa portionshown in section.

Figure 3 embodiment ofV the invention which includes a one-pin starwheel and' a-cross-grooved v'ca mto be driven'l thereby, constituting vaGeneva stop movement." i l Figure 4 is an elevation of the same, takenat rightrangles toFigureB. -l l Figure 5 is a side elevationsimilar toFigure 1 butl taken partly in section, as indicated 'at line 5 5 on,Figure 6,'andshowing a modifiedfior'n of the invention. f i i Figure 6is a tcp planviewpartly in section;

is-a side elevation showing another 4 indicating theinodeoffoperationofthe structure taken mainly as' indicated at line 6;;6 ori-Fig I ure 5.Y

Figure 7 is a plan view showing' a grooved"drivA ing wheel and astarwheel having straight cylindrical'4 pins or teeth to cooperatetherewith.

Figure 8 is a-detail cross-sectionthrough one of thepins of the starvwheel shown inFigure?, being taken on a larger scale. Y. Figure 9 is apartly diagrammatic plan'view shown in Figures 5 and 6.l 1 r lFigure1'0l is a cross-section of one of theiteeth of the star Wheel of Figure9 takencn an enlarged Figure 117 is an isometric viewv on alarge scalefor developing the correct form of'tooth for the star wheel of Figures 5and 6. l Figure 12is a fragmentary and partially diagrammatic viewvshowing a portion of av grinding wheelv andi illustrating'a method ofproducing a star-wheel tooth in accordance with thisinven- As shown inFigures 1"and2, I isav multiple` pin star wheel;r the pins'or teeth? andthe body li thereof beingfmade integral, and 'the pins beingoi conicalform. 'i The hub 4'o'fthe star wheel may be connected by meansof a'cross-pinv 5 with' a shaft 6 and with a sprocket, of which a fragmentisshown'at 1,' if the star 4wheel is employedior driving the filmof acinematographicapparatus. The pins or teeth'2 `meshwith'acorresp'onclinglt7 tapered camgroove' of Aa driving wheel Ei; andit may be understood that the star `wheel izrcr the cam wheel' 9, vorboth of them,l may bemou'nt- 'ed .forl "adjustment toward and fromeach'other, as indicated by .thearrows a and b on' Figure 2,

for Vtaking fup wear' due to the-friction between the cam grooveran'dthe tapered pins or teeth 2*'of the starwheel.' i

` This same principle of adjustment for, wear may be 'applied' to aAone-pin starawhel ofl'the p ty-pe-shownf'at I"infFigures 3' andlfi,whichfhas a conical"'pin"12 projectingfro'm the kface oi lthe wheel; anda 'suitable"`arcuatef,rim orv fiange v3, which cooperate to'provideastep-by-step action ofthe Adriven shaft 6,' the pin `2\`engagin'gyin across=section 3 in the'cam wheel 9 when the' driv'- ing Shaft `li) `isl'tatedi In this-structure Atliepin 2 `istapered,-a'nd thecross-grc'oves`8 are corre# spondingly tapered to t the pin; andthe resulting wearon'the pinoro'nthe grooves may-fb@ taken` upbyadjustment of the shafts6' and I U,

or one' cfvtheni,` so as'to" shiftv the pin and 'grooves toward eachother finthe vdirections indicated by arrowsaandbonFigure' 3. f i' 'lAlthoughconicalpins will initiallyexperience only lineary contacts withtheir grooves', the tapered form of such'pins permits oftheadjustabilityindicated;I and the wear which requires the adjustment"incidentallyjtends to' flatten the sidesA ofthe-pins and increases theirareas of contact.V -But for the'purpose of obtaining at the outsetsomething more thanlinear contacts,"we havefdeveloped another formy ofmultiple-tooth star wheel, employing the basic idea of a tapered groovecooperating with a tapered pin. This improved structureis shown inFigures 5 and 6. In this form it is contemplated that the entire starwheel should be punched from relatively thin 'metal in one piece, andsince it is important to reduce the weight and momentum oi the star`wheel as much as possible, the punched blank may include holes I formedin the base 'of each tooth 2, where the tapered form of the teeth allowsof the removal of this metal without weakening of the wheel structure.

y yside Walls of the cam groove.

For determining the nal or ideal shape forthe teeth 2 of the star wheelwe may first observe the operation of a simple type,'such as that shownin Figures 7 and 8 in whichthegroove '8 of the cam wheel 9 is ofrectangular shape, and in which the pins or teeth of the followerwheel..areindi' cated as cylindrical in cross-section. Upon rotation ofthe shaft I0 and wheel 9 the "drunken screw" or cam groove@ willcauseintermittent roration of the star wheel :I in the direction of `thearrow shown adjacent thenctoon'Figure 7. .The pin f2' willstandimotionless during its engagement with the straight portion of thegroovcfl. and will be caused to .shift to the right as it is encounteredby the inclined portlonor thread-.8'`- Figure '7 indicates schematicallyvseveral successive positions of thepin lfrom which itwill be evidentthat said rpin y2' ywill undergo slight bilateral wear by its contactAwith the .straight portion of thegroove I, but that 'the inclined orthread portion 8 will impose relatively heavy wearat the'left and-upper.Portion of thepin.- as

viewed in its several positions .in Figure 7, and u liso lattherightand'ilower portion-due :to the oblique position `of the walls'of thethread -8' which are inclined totheaxisfof lrotationat th angle a.

While ythe pin 2'of ithestar wheel :isbeing shifted inthe thread portionofthe cam groove themen-pini isl'ed'intoathe adiscentinclined thneadportion f'tof the grooveand-alsoexperiences .severe-wear Aunits iupperleft and lower right-hand portions, asvlesredatthe-seversipositions'indicaterlV inn-Figure .7 .for thejpin 2. The deformation 'ofthe originally `cylindrical cross sectioni which eventuallyrcsults, :forexample, in thecase of pin 2f. is indicated bysthecross-sectional viewof Figure 8, and itfwillrbe remnld that in a motion'picturemachinesuch'deformation will cause irregularities in the step-by-stcpmovement of the lm vhand andiconsequent shifting or vibration of the.successive tramesiof .the picture during proiection, such `asio'seriously impair the vqualityof the Even though the'deformed pinsmavhaveat-surfaces at opposite sides, these faces, worn downfromtheoriginally cylindril shape, :will fit 'loosely between the wallsofthegrooveland allow-undesirable` play in the operation.

Fromrthe foregoingit willbe evident Lhateven a tapered pin or .tooth yofthetype' shown in Figures 5 and 6wiil require-n slightbut impor-ftant,reiinementlnshaPefOr insuring-its smooth passage through thethreaded'portions Band 8," of thecam groove, as-shown'inFlgure 9. Thisgure, Varranged vin the same schematic. manner as Figure the successivepositions oi thelpins 2in the inclined portions ofthe cam groove, andshowsthatif the side wallsoi the groove .were resilient theywould haveto yieldzto permit the` pins to pass. Since they arenotresilient.certain` portions of the pins must be cut on' in orderthat theymay nttheseAportions-of 4The ideal geometrical shape of the curved sur- -facesc and d, as developed on an isolated pin or tooth 2, is conical, asindicated in Figure 11, these `surfacesbeing portions of the surface ofa truncated cone drawnin dotted outline, with its axis denoted by theline I I. This being so, the proper peros-section of the tooth will bethicker at the root than at the outer end, so that opposite facesotthestar wheel will not be strictly parallel at the-teeth 2. Figure vl1indicatesrthe angle of inclination of `the narrow side walls of thetoothto the axis II as and the angle of inclination of the broader side wallsis shown as about /2 to insure that the conical surfaces c and-d shallmerge properly into theiiat `faces of the tooth. Such a pin or toothprovides ideal flat seating against thestraight side walls of ther camgroove 8, and efcient curved bearing surfaces for'contact with theinclinedor threaded portions 8 and 8".of thel groove, although it may beunderstood that the approximation to ideal-shape, indicated in'Figurel0, will also give reasonably good results. But the higher cost ofAproduction of the star wheel with beveled faces, suggested by Figurell, will be compensated by its more nearly ideal operating qualities.

.In View of the `foregoing, we have shown in Figure l2 a means andmethod of producing a star wheel with teeth formed either as shown inFigure 10 or as indicated in Figure 11. This includes a grinding orcutting wheel I2, having a groove 13,01. a diameterv and shapecorresponding to those of the cam wheel Il. except 'that the groove ,isa straight one, `without, inclined or threaded portions. This grindingvwheel is rotated on its shaft I 4, and a star wheel I,.formed from .ablank like that shown in Figure 6, may be nished by inserting its teeth,one after another, in the groove of -this'grinding wheel, and turningeach tooth within the groove slowly, as indicated bythe arrows throughthe angle `a: as the `grinding .proceeds to round oif'two oppositediagonal corners of the tooth.

Whereas a conical pin is initially limited to a line contact, anddevelops a broader contactface only at the expense of lateral playbetween the side walls of the cam groove, tapered pins made 1naccordance with Figure 10 or 11 have the ad.- vantageof broad Vbearingsurfaces from the beginning and throughout successive adjustments forwear, such as are indicated by the arrows a, b in Figure 6. It willalsobe'evident that when the star'wheel is `made from a sheet metal platewhich can be initially formed by.a single punching operation, withsubsequent rening of the teeth by the relativelysimple grindingoperationl the cost of production can be made even less than that ofstar wheels vwith conical pins or teeth. For the particular use forwhich these star Wheels have been designed the sheet material from whichthey are made may be about one-sixteenth of an inch in'thickness, orslightly greater, if 'the tapered form of tooth shown in Figure l1 is tobe employed.

f "i c. 2,332,509

v-Z'Clie linvention is not to be understood as re Y stricted to the.embodiments and details herein set forth, since these may be rnc'cliedby those y rskilled in the art-without departing from the spirit andscope of the invention; rather, the invention is intended'to embrace`all changes and variations Vof structure which -might be V'includedwithin the scope ofthe appended claims.

y We claim as our invention:

l.' In a mechanism for producing a step by step action, the combinationwith a multiple pin star y wheel having substantially'tapered pins, of acam having one correspondingly. tapered groove, said substantiallytapered pins being of 'approximately 'rectangular' section but with` twodiagonally opposite corners of` this section cut off along curves.

cam `havin-g a correspondingly tapered groove which includes straightportions andthreadpon tions inclined to the plane of the straightportions of the groove, said substantially tapered pins k I being' ofapproximately rectangular se'ction,'two diagonally opposite cornersofvthis section being cut orf 'along curves with adjacent portions' ofthe sectionlat the tapering sides of each pin remaining to an extentsuicient to insure a snug rit be tween' said pins and the'straight aswell as the thread portions of said'groove.

.4. In combination, a star wheel and a grooved ycarn for producing astepby-step action, the star 2. In a mechanisml for producing a step bystep Vacton',th 'a combination with a multiple pin star wheel havingsubstantially tapered' pins, of a cam having a groove of correspondinglytapered crosssection and of a contour which .includes thread portionsinclined or deflected from a plane perpendicular to the axis ofrotation, said substanltially tapered pins being of approximatelyrectangular section but with two diagonally oppositer corners of thissection cut oivalong curves whererby the diagonal width of eachvpin tssnugly be- 4 stantially tapered pins,` and the cam havingv a;

correspondingly tapered groove, said taperedpins being of approximatelyrectangular cross section v. with diagonally opposite "corners of thissection rounded 01T,k and means-for adjusting one of said` wheel havingsubstantially tapered pins, and the cam having a correspondinglytaperedgro'ove,said substantiallytapered pinsbeing of approximatelyrectangular cross-section with ldiagonally opposite corners of thissection rounded off.-

5.'In combination, a unitary star Wheellelement and a grooved camelement'for producing 'a step-by-step action,.the star Wheelrhavingsubelements bodily toward the'other to eliminate the tween the Walls ofthe deilected or thread portions n y of the cam groove.` 1 Y i 3. In amechanism for producing a step by step l action, the combinationwith amultiple pin-*starv wheel having substantially tapered pins', of a andthe tapered groove.

4 YHaar/Mir A. mi yQT'ro R. NEMETH, c

play caused vby wear between saidtaygnered` pinsk

